we were given a function of y=(x-a)(x-b)(x-c) and were told to add in our own numbers i chose y=(x-8)(x+5)(x-3). can some one show me the working to get it to a cubic and then the derivative

Aug 25th 2008, 04:37 PM

Jhevon

Quote:

Originally Posted by psychosocial for life

we were given a function of y=(x-a)(x-b)(x-c) and were told to add in our own numbers i chose y=(x-8)(x+5)(x-3). can some one show me the working to get it to a cubic and then the derivative

lets say it was (x - 8)(x + 5), could you expand that?

expand the first two first, and then multiply what you got by the (x - 3). how? first multiply everything by the x and then multiply everything by the -3

when finding the derivative, all that is needed is the power rule: $\displaystyle \frac d{dx} x^n = nx^{n - 1}$

and of course, if there are constants in front of the x's, you just leave them and multiply what you got by them since $\displaystyle \frac d{dx}[c f(x)] = c \frac d{dx}f(x)$. here, your $\displaystyle f(x)$ is $\displaystyle x^n$

(why did you choose such big numbers? :p)

Aug 25th 2008, 05:04 PM

psychosocial for life

thanks for the help

Quote:

(why did you choose such big numbers? :p)

Dont know but regreting it now

Aug 25th 2008, 05:05 PM

Jhevon

Quote:

Originally Posted by psychosocial for life

thanks for the help

Dont know but regreting it now

okie dokie.

post your answer when done, we'll check it for you

Aug 25th 2008, 06:30 PM

psychosocial for life

for some reason it still isnt working out right could you please show me the working out so i can workout what im doing wrong. i just cant work it out (Crying)

Aug 25th 2008, 06:58 PM

Jhevon

Quote:

Originally Posted by psychosocial for life

for some reason it still isnt working out right could you please show me the working out so i can workout what im doing wrong. i just cant work it out (Crying)